The present invention relates to an AV selector for changing the connection between pieces of AV equipment such as VTRs (Video Tape Recorders), MDPs (Multi Disk Players) and TVs (television receivers).
In recent years, pieces of AV equipment such as TVs, VTRs, MDPs, AV selectors, speaker systems and amplifiers can be connected to each other by not only video and audio cables for exchanging video and audio signals, respectively, but also by control-signal lines for exchanging control signals. Such connection allows pieces of AV equipment to be integrated into an AV system.
Operations of pieces of AV equipment constituting such an AV system can be interlocked with each other by exchanges of control signals. In other words, when an operation to play back a video or audio signal at a VTR or an MDP is started, for example, a control signal notifying the start of the playback operation is output to a TV or an amplifier and a speaker system. Receiving the control signal, the TV or the amplifier and the speaker system turn on their power, allowing the reproduced video or audio signal to be displayed or to be output.
Typically, the user must build an AV system by himself by connecting pieces of AV equipment to each other while referring to user manuals and checking signal names of the pieces of AV equipment to be connected which are normally written in close proximity to connectors of the AV equipment. As a result, where many pieces of AV equipment are to be connected to each other, a problem arises in that the task is arduous.
On top of that, the pieces of AV equipment may not be connected correctly, resulting in an AV system that does not operate normally in an interlocked manner. As a result, another problem arises in that the user thinks mistakenly that a malfunction has occurred in the AV equipment.
Furthermore, there is an AV system which can check the connection among pieces of AV equipment constituting the AV system and notify the user of any incorrect connection. An example of such an AV system is disclosed in Japanese Patent Laid-Open No. H03-66089 dated Jul. 31, 1989.
In the case of the AV system disclosed to the public through the patent described above, however, an alarm sound is merely generated along with an alarm message displayed on a screen by means of an audio synthesis unit and a character generating circuit, respectively, for a detected miswired external signal, allowing the incorrect wiring state of an external electronic device to be identified in a simple way.
The configuration of the AV system is described in concrete terms as follows.
When an external audio (A) or video (V) signal does not match a connector pin or is not available due to incorrect wiring, a signal detection unit controlled by a signal output by an A/N control logic unit detects the state of the video (V) or audio (A) signal output by an A/V switch unit. The A/N control logic unit outputs an incorrectly wired signal, applying the incorrectly wired signal to a pin of an audio switch unit. The incorrectly wired signal is also applied to a pin of remote-control adjustment unit as well. A signal output by the remote-control adjustment unit is then supplied to a pin of the audio switch unit through the audio synthesis unit before being transmitted to a speaker for generating a warning sound through an audio-signal processing unit and an amplifier. In addition, the signal output by the remote-control adjustment unit is also supplied to the character generating circuit for controlling a CRT driver. The CRT driver, in turn, displays characters `MISWIRING` on the screen of a CRT.
Such an AV system requires a signal generating circuit for producing signals used for checking video and audio cables connecting the pieces of AV equipment to each other. In addition, a control signal for controlling the signal generating circuit is also required to control signals for controlling the interlocked operations of the AV equipment. As a result, still another problem arises due to the fact that the AV system becomes large in size and the control becomes complicated.
In addition, the complicated control in turn gives rise to still another problem that it takes time to check the connection among the pieces of AV equipment.
On the other hand, connectors are provided at both ends of each of video and audio cables as well as control lines for connecting pieces of AV equipment. By fixing each cable/line connector into a connector provided on the AV equipment, electrical connection is established among the pieces of AV equipment.
When considering connection between a TV and a VTR, for example, it is thus necessary to connect a video input connector, an audio input connector, a video output connector, an audio output connector and a control signal connector of the TV to a video output connector, an audio output connector, a video input connector, an audio input connector and a control signal connector of the VTR, respectively, by cables.
In this case, however, a connector attached to an end of a cable is generally not discriminative. That is to say, the connector is not designed to handle a plurality of signals. As a result, a connector can be fixed into a wrong connector. To be more specific, the audio output connectors of the TV and the VTR can be plugged in each other mistakenly, for example, even if the video input connector of the TV is fixed into the video output connector of the VTR correctly.
When there are many incorrectly wired pieces of AV equipment, it is not easy to correct the wiring while verifying the connection even if the user is notified of the existence of incorrect wiring as described above.